ICU SEDATION GUIDELINES



DEEP VENOUS THROMBOSIS PROPHYLAXIS

IN SURGICAL PATIENTS

SUMMARY

Critically ill patients are at significant risk for deep venous thrombosis (DVT) as a result of inactivity, immobilization, vascular injury, and/or hypercoagulable states. DVT may progress to thrombophlebitis or pulmonary embolism (PE) with increased morbidity and mortality. Appropriate DVT prophylaxis varies with the patient’s risk factors and physiologic state.

OVERVIEW

Venous thromboembolism (VTE) is associated with significant morbidity and mortality as well as an enormous economic expense. Approximately 200,000 cases of VTE occur annually of which one third involve pulmonary embolism (PE) accounting for 10% of hospital deaths (1). Hospitalization for an acute medical illness increases the risk of VTE almost 8-fold (2). The 30-day mortality of deep venous thrombosis (DVT) is 6% and that of PE is 12% (3). The annual economic burden of VTE is estimated at $1.5 billion per year. Critically ill patients are at significant risk for the development of DVT as a result of inactivity, immobilization, vascular injury, and/or hypercoagulable states. DVT prophylaxis is indicated in the majority of critically ill patients with the appropriate therapy being determined by the patient’s risk factors and physiologic state.

***DVT PROPHYLAXIS SHOULD BE CONSIDERED IN ALL PATIENTS

AND INITIATED AT THE TIME OF IMMOBILITY***

The overall incidence of DVT in surgical patients is 19-29% with patients with malignancy being at highest risk. PE is clinically recognized in 1.6% of patients with an additional 0.9% being recognized only post-mortem. Knowledge of specific risk factors forms the basis for appropriate prophylaxis. The rationale for thromboprophylaxis is based on the high prevalence of DVT among hospitalized patients, the clinically silent nature of the disease in the majority of patients, and the morbidity, costs, and potential mortality associated with DVT (4,5).

PE is the third most common cause of death in trauma patients who survive beyond the first day (6). Without prophylaxis, patients with multi-system or major trauma have a risk for DVT that exceeds 50%, and a risk of fatal PE of approximately 0.4 - 2.0% (8-11). The traumatically injured are at high risk for developing DVT and PE as a result of endothelial injury and prolonged immobility. DVT is seen in 69% of lower extremity fractures, 62% of spine fractures, 54% of major head injuries, and 40% of patients with blunt thoracoabdominal trauma (6). Patients with single-system, non-orthopedic injuries have a lower risk of DVT than those with multiple injuries or with lower extremity fractures.

Clinical risk factors for DVT and PE in the surgical patient

• Prolonged immobility

• Age > 40 years

• Stroke

• Paralysis

• Previous DVT

• Malignancy and its treatment

• Major surgery (particularly involving the abdomen, pelvis, and lower extremities)

• Obesity

• Spinal cord injury

• Lower extremity or pelvic fracture

• Need for a surgical procedure

• Increasing age

• Varicose veins

• Cardiac dysfunction

• Indwelling central venous catheters

• Inflammatory bowel disease

• Nephrotic syndrome

• Pregnancy or estrogen use

• Congenital and acquired thrombophilic disorders (Factor V Leiden, lupus anticoagulant, protein C/S deficiency, etc…)

• Femoral venous line or major venous repair

• Prolonged immobility

• Duration of hospital stay

In many patients, multiple risk factors may be present with the total risk being cumulative. For surgical patients, the incidence of DVT is proportional to the risk factors present and the risk associated with the procedure itself. Procedure-related risks include: the location, technique, and duration of the procedure; the type of anesthetic; the presence of infection; and the degree of postoperative immobilization.

Despite appropriate DVT prophylaxis, surgical patients may still develop both DVT and PE. A recent case-control study identified five independent predictors of in-hospital DVT despite chemoprophylaxis (12). These included hospitalization for cranial surgery, intensive care unit admission, admission leukocyte count >13,000/mm3, presence of an indwelling central venous catheter, and admission from a long-term care facility. In the presence of such risk factors, aggressive efforts to achieve DVT prophylaxis should be maintained.

Alhazzani et al. recently performed a systematic review of studies involving medical-surgical ICU patients who received either any form of heparin [low dose unfractionated heparin (LDUH) or low molecular weight heparin (LMWH)] or no anticoagulant prophylaxis evaluating the incidence of DVT, pulmonary embolism, major bleeding , or mortality (13). Any heparin prophylaxis compared with no prophylaxis reduced rates of DVT (relative risk [RR] 0.51; p 30), higher doses may be warranted. Due to the potential for delayed elimination in patients with renal impairment (creatinine clearance < 30 mL/minute), dose adjustment to 30 mg SQ q 24 hours is recommended. Dosing information for patients undergoing hemodialysis is lacking. Anti-Xa levels have been used to guide therapy (23). However, there is a relative lack of outcome data supporting this practice and the target range is not well-established. Despite these limitations, monitoring anti-Xa activity may be useful in populations where dosing is not well-established and the use of unfractionated heparin is not feasible. If obtained, levels should be drawn four hours after the third or fourth dose. The goal anti-Xa level for DVT prophylaxis is 0.1 to 0.3 IU/mL (24).

Intermittent pneumatic compression devices (IPC) - Cost: $50 / admission

IPC is an attractive method of prophylaxis because of the lack of hemorrhagic complications. Several small studies have demonstrated that IPC is effective in reducing DVT in general surgery patients and in surgical patients with malignant disease. In trials comparing IPC with LDUH, both agents produced similar reductions in DVT (25). However, compliance with these devices is low and it is not proven that IPC prevents PE (or even proximal DVT) in general surgery patients.

IPC cannot be recommended as routine prophylaxis in trauma, due to a lack of data. IPC may be beneficial as the initial prophylaxis in patients with intracranial hemorrhage or other injury who are at high risk for bleeding and can be utilized until anticoagulants, such as LMWH, may be safely initiated (26).

Graded compression elastic stockings (ES)

ES (e.g., Jobst( stockings NOT TED hose) reduce the incidence of leg DVT and enhance the protection provided by LDUH. Insufficient data exists to assess their effect on proximal DVT and PE however. Combining ES with other prophylactic agents, such as LDUH, appears to give better protection against DVT than either approach alone (27,28). ES cannot be recommended as routine prophylaxis in trauma, due to a lack of data. They may be beneficial as the initial prophylaxis in patients with intracranial hemorrhage or other injury who are at high risk for bleeding and can be utilized until anticoagulants, such as LMWH, may be safely initiated (26).

Venous foot pumps (VFP) - Cost: $50 / admission

Intermittent plantar compression, using VFP, produces hemodynamic effects on lower extremity emptying similar to that of IPC while also stimulating fibrinolytic activity (25). The efficacy of these devices has been called into question by a randomized trial showing DVT rates three times greater with VFP compared to IPC. A recent cohort study demonstrated a venographically proven DVT rate of 57% in major trauma patients receiving prophylaxis with bilateral VFP. Compliance with these devices is poor (29). At the present time, VFP cannot be recommended in trauma patients.

Table 1: Surgical Patients: Risk Stratification and Therapeutic Recommendations

|Population |Recommendation |Alternatives |

|High Risk | |Heparin 5000 units q 8 hrs ($) |

|(Polytrauma, VTE history, obesity, critical |CrCl > 30 mL/min | |

|illness) |Enoxaparin 30 mg BID ($$) |Fondaparinux 2.5 mg daily ($$$$) |

| | |(for patients with history of heparin induced |

| |CrCl< 30 min |thrombocytopenia; contraindicated in patients |

| |Enoxaparin 30 mg daily ($) |with CrCl < 30 mL/min) |

|General Surgery | | |

|Abdominal/Pelvic Surgery |CrCl > 30 mL/min | |

|Cardiothoracic Surgery |Enoxaparin 40 mg daily ($) | |

|Trauma Surgery | | |

|Orthopedic Surgery |CrCl< 30 min | |

| |Enoxaparin 30 mg daily ($) | |

|Neurosurgery |Heparin 5000 units q 8 hrs ($) | |

|Spine Surgery | | |

REFERENCES

1. Heit JA. Venous thromboembolism epidemiology: implications for prevention and management. Semin Thromb Hemost 2002, 28(Suppl 2):3-13.

2. White RH. The epidemiology of venous thromboembolism. Circulation 2003; 107(Suppl):I4-I8.

3. Heit JA, Silverstein MD, Mohr DN, et al. Predictors of survival after deep vein thrombosis and pulmonary embolism: a population-based, cohort study. Arch Intern Med 1999; 159:445-453.

4. Kearon C, Kahn SR, Agnelli G, Goldhaber S, Raskob GE, Comerota AJ. Antithrombotic therapy for venous thromboembolic disease: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; 133(6 Suppl):454S-545S.

5. Clagett, GP, Reisch, JS. Prevention of VTE in general surgical patients: result of a meta-analysis. Ann Surg 1988; 208,227-240.

6. Pasquale M, Fabian TC, and the EAST Ad Hoc Committee on Practice Management Guideline Development. Practice management guidelines for trauma from the Eastern Association for the Surgery of Trauma. J Trauma 1998; 44:941-957.

7. Huber O, Bounameaux H, Borst F, et al. Postoperative pulmonary embolism after hospital discharge: an underestimated risk. Arch Surg 1992; 127:310-313.

8. Montgomery KD, Geerts WH, Potter HG, et al. Practical management of VTE following pelvic fractures. Orthop Clin North Am 1997; 28:397-404.

9. Hoyt DR, Simons RK, Wincell RJ, et al. A risk analysis of pulmonary complications following major trauma. J Trauma 1993; 35:524-531.

10. Frezza EE, Siram SM, Van Thiel DH, et al. VTE after penetrating chest trauma is not a cause of early death. J Cardiovasc Surg 1996; 37:521-524.

11. Geerts W, Jay R, Code K, et al. Venous foot pumps as thromboprophylaxis in major trauma. Thromb Haemost 1999; 82 (suppl):650-651.

12. Wang TF, Wong CA, Milligan PE, Thoelke MS, Woeltje KF, Gage BF. Risk factors for inpatient venous thromboembolism despite thromboprophylaxis. Thromb Res 2014;133:25-29.

13. Alhazzani W, Lim W, Jaeschke RZ, Murad MH, Cade J, Cook DJ. Heparin thromboprophylaxis in medical-surgical critically ill patients: a systemic review and meta-analysis of randomized trials. Crit Care Med 2013; 41:2088-2098.

14. Kiil J, Axelsen F, et al. Prophylaxis against postoperative pulmonary embolism and deep vein thrombosis by low dose heparin. Lancet 1978; 1:1115-1116.

15. Sagar S, Massey J, Sanderson JM. Low dose heparin prophylaxis against fatal pulmonary embolism. BMJ 1975; 4:257-259.

16. Etchells E, McLeod RS, Geerts W, et al. Economic analysis of low dose heparin vs the low molecular weight heparin enoxaparin for prevention of venous thromboembolism after colorectal surgery. Arch Intern Med 1999; 159:1221-1228.

17. Geerts WH, Jay RM, Code KI, et al. A comparison of low –dose heparin with low-molecular weight heparin as prophylaxis against VTE after major trauma. N Engl J Med 1996; 335:701-707.

18. Norwood SH, McAuley CE, Berne JD, Vallina VL, Kerns DB, et al. A potentially expanded role for enoxaparin in preventing venous thromboembolism in high risk blunt trauma patients. J Am Coll Surg 2001; 192:161-167.

19. Schwarz TH, Quick RC, Minion DJ, Kearney PA, Kwolek CJ, et al. Enoxaparin treatment in high-risk trauma patients limits the utility of surveillance venous duplex scanning. J Vasc Surg 2001; 34:447-452.

20. Dolay K, Kurtoglu M, Guloglu R, Necefli A. Use of low molecular weight heparin enoxaparin) in preventing thromboembolism in multiple trauma patients. Br J Surg 1998; 85(Suppl 2):105

21. Norwood SH, McAuley CE, Berne JD, Vallina VL, Kerns DB, et al. Prospective evaluation for venous thromboembolism in patients with intracranial hemorrhagic injuries. Arch Surg. 2002; 137:696-702.

22. Kim J, Gearhart MM, Zurick A, Zuccarello M, James L, et al. Preliminary report on the safety of heparin for deep venous thrombosis prophylaxis after severe head injury. J Trauma 2002; 53:38-43.

23. Mayr AJ, Dunser M, Kochberger S, et al. Antifactor Xa activity in intensive care patients receiving thromboembolic prophylaxis with standard doses of enoxaparin. Thromb Res 2002; 105:201-4.

24. Knudson MM, Morabito D, Paiement GD, Shackleford S. Use of low molecular weight heparin in preventing thromboembolism in trauma patients. J Trauma 1996; 41:446-459.

25. Wille-Jorgensen P, Thorup J, Fischer A, et al. Heparin with and without graded compression stockings in the prevention of thromboembolic complications of major abdominal surgery: a randomized trial. Br J Surg 1985; 94:21-25.

26. Hirsh J, Warkentin TE, Shaughnessy SG, et al. Heparin and low-molecular-weight heparin: mechanisms of action, pharmacokinetics, dosing, monitoring, efficacy, and safety. Chest 2001; 119:64-94S.

27. Torngren S. Low dose heparin and compression stockings in the prevention of postoperative deep venous thrombosis. Br J Surg 1980; 67:482-484.

28. Clagett GP, Anderson FA, Geerts W, et al. Prevention of VTE. Chest 1998; 114 (suppl):531s-560s.

29. Anglen JO, Goss K, Edwards J, et al. Foot pump prophylaxis for deep venous thrombosis: the rate of effective usage in trauma patients. Am J Orthop 1998; 27:580-582.

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RECOMMENDATIONS

• Surgery (General / Trauma / Vascular / GYN / Urology)

➢ Level 1

▪ Patients should receive DVT prophylaxis using low molecular weight heparin (LMWH) as soon as is clinically safe.

➢ Level 2

▪ Patients at low-risk for DVT require only early ambulation.

▪ Patients at high-risk for bleeding should receive mechanical prophylaxis with intermittent pneumatic compression devices (IPC) or venous foot pumps (VFP).

▪ Patients at very high-risk for DVT should receive LMWH combined with IPC or VFP.

▪ Inferior vena cava filter (IFC) insertion is not recommended for primary prophylaxis (see IVC Filter guideline).

➢ Level 3

▪ When using LMWH, dose adjustment and/or anti-Xa monitoring should be considered for weight < 45 kg, morbid obesity, or renal impairment (CrCl ................
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